Method and Apparatus for Inserting a Tubular String into a Well

ABSTRACT

A valve to act as a barrier to fluid movement in a tubular is provided. A flapper in the valve may be opened by application of a selected pressure differential across the flapper. The flapper opens to allow a cylinder to shift and cover the open flapper. A method of placing a tubular string within a well using the valve as an isolation valve to form gas filled chambers for floating the tubular string into the well is also disclosed.

BACKGROUND OF INVENTION

1. Field of the Invention

This invention relates to a differential pressure-activated valve in a sub to be placed in a tubular of a well before the tubular is placed in the well. More particularly, a barrier valve in a sub is provided to seal pressure in both directions, to open in response to a pressure applied uphole, to provide a full opening diameter of the tubular and to be locked in the open position.

2. Description of Related Art

Valves are used in diverse applications in the tubulars of wells. (“Tubulars” includes casing, liners and tubing.) For example, safety valves are placed in tubing that are designed to close if flow upward through the tubing is otherwise uncontrolled. Sliding sleeves to form valves are placed in casing to be opened or shut by devices placed inside the casing, and valves are placed in casing or tubing of complex (or “smart”) wells to control flow rate from different laterals of the well. Examples of valves for wells are in U.S. Pat No. 8,622,336 and in U.S. Pat No. 8,757,268. Further examples of valves to be inserted in tubulars are provided in U.S. Pub. No. 2009/0272539, disclosing a valve in a tubular that may be mechanically closed, and U.S. Pub. No. 2009/0229829, disclosing a valve having a valve element on trunnions that move along a track.

One type of valve used in casing is a “float valve,” which is used at the shoe (bottom) or distal end of every casing that is cemented in a wellbore to prevent flowback (or U-tubing) of more dense cement slurry when pressure is released at the surface after displacing the cement slurry with water. A float valve is normally a simple ball check valve. The float valve may also be used in the process of “floating” casing into a well. “Floating” casing is used to allow casing to be placed in horizontal wells with less weight of the casing and less frictional resistance as the casing is placed in a horizontal segment of a well. Floating casing is accomplished by placing nitrogen or air inside the casing to decrease the weight of the casing. This facilitates inserting the casing over longer horizontal sections. One operator's experience with “floating” a tubular into a well is described in the paper “Statoil uses flotation of 10¾-in, liner to reach beyond 10 km in Gullfaks Field,” Drilling Contractor, May/June 2007, pp. 66-74.

There are risks associated with the process of floating casing or a liner into a well. Leaks in the tubular may occur that allow liquid to enter the tubular and result in the casing or liner becoming stuck in the well before it is properly placed. For this and other operations in drilling and running tubulars into wells, a valve that can be placed at selected locations along a tubular string and opened to the full diameter of the tubular by a pressure increase at the surface of the tubular is needed. A series of valves, each of which may be called a “cascade barrier valve,” may be preferred. This valve, when open, should allow movement of downhole tools through the tubular without restriction. When closed, cascade barrier valves at selected locations along the casing may be used to prevent fluid leaking in and filling a long interval of the casing while it is being floated into a horizontal well.

In drilling or working on vertical, directional or horizontal wells, a plurality of pressure barriers is needed to decrease the risk of uncontrolled flow from a well. Valves in tubulars in wells that form a pressure barrier until opened by a surface operation and then are locked open to provide full inside diameter also offer wide opportunities for increasing well safety.

What is needed is a valve in a sub that will seal pressure in both directions, open in response to a selected pressure applied uphole, provide a full opening diameter of the tubular when open and be locked in the open position.

BRIEF SUMMARY OF THE INVENTION

A full-opening valve in a sub for placement in a string of casing, liner or tubing that is opened by a selected pressure applied from the surface is provided. A shear ring or pin is selected to shear at a selected differential pressure in response to a pressure increase at the surface and allows a lower flow tube having the inside diameter of the tubular to move axially. This allows an upper flow tube having the same inside diameter to move axially, pushing open a flapper having dual sealing surfaces, which seal on the adjacent ends of the upper and lower flow tubes. Movement of the upper flow tube may push a pin supporting the flapper to move through a groove to a position where the flapper can move to the open position, where it conforms to the shape of the inside of the tubular. The flapper is locked in the open position for the life of the valve by operation of the upper flow tube and a snap ring, which locks the upper flow tube in position over the open flapper. The valve may be used to provide a pressure barrier in the casing during floating of the casing into a horizontal well or after the casing is in place or it may be used in tubing to prevent flow in the tubing in either direction until a selected pressure is applied at the surface. Valves may be adapted to open at a differential pressure across the valve which varies over a broad range of differential pressures within the operating pressure of the valve.

The valve may be closed during deployment and once activated is locked in the open position.

The isolation valve may be used by itself to provide a barrier in either the casing or the tubing, or may be used in conjunction with additional valves to form chambers in the tubular string.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a cross-section view of valve sub 10 in the closed or run-in condition.

FIG. 2 is a cross-section view of valve sub 10 after shearing of a disk or pin and before opening of the flapper.

FIG. 3 is a cross-section view of valve sub 10 in the open position.

FIG. 4 is a cross-sectional view of the valve sub 10 at cross-section “4” in FIG. 1.

FIG. 5 is an isometric view of the flapper in closed position with outer parts removed from the drawing.

FIG. 6 is an isometric view of the flapper in the partially-open position with outer parts removed from the drawing, identifying upper and lower sealing surfaces on the flapper.

FIG. 7 is an isometric view of the flapper in open position with outer parts removed from the drawing.

FIG. 8 is a perspective view of the flapper.

FIG. 9 is a side view of the flapper positioned between the upper and lower flow tube.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, isolation valve 10 has lock housing 12, which is adapted to be joined in a tubular string, normally by pipe treads (not shown) and which preferably has the same inside diameter as the tubular string. Preferably, the outside diameter of the isolating valve is not more than the outside diameter of couplings in the tubular string. Seal 13 provides a barrier between lock housing 12 and upper spring housing 15. Upper flow tube 18 preferably has the same inside diameter as the minimum inside diameter of lock housing 12 and is adapted to slide within upper spring housing 15. Upper flow tube 18 may have internal shifting profile 11. Shifting profile 11 may be used for optional manual shifting to open flapper 24 and allow intervention from uphole by jarring or other mechanical force if isolation valve 10 is not operating properly. Shifting profile 11 a may be the well-known “B-style” shifting profile, for example. Bearing 14 contacts upper coil spring 16 and allows low-resistance rotation of the end of the spring as it is compressed or expands. Snap ring 17 is compressed in the radial direction in the position shown in FIG. 1 and is adapted to slide within upper spring housing 15 and once it finds the spring housing 15 lock ring profile 17 a, the snap ring 17 will lock the upper flow tube 18 open. Seal 21 perfects a seal between housing adapter 20 and lower spring housing 25.

Flapper 24 is supported by flapper pin 22 locked between the upper and lower flow tubes and flapper 24 is free to move along the axis of lower flow tube 29 as pressure is applied uphole (from the left side of FIG. 1) to apply a known force to shear ring or pin 30. Only a small displacement is required for shearing the ring or pin, so the ring or pin can be sheared even if a normal volume of liquid is on the low-pressure side of flapper 24.

Flapper 24 is supported within a flapper housing 35 best shown in FIG. 5. Key 34 maintains upper flow tube 19 and flapper housing 35 in axial alignment and key 44 maintains lower flow tube 29 in axial alignment with the flapper housing 33. A shock absorbing element 33 is secured to flapper housing 35 by screws 42.

Referring to FIG. 2, shear ring or pin 30 is shown after shearing in the axial direction, with separation into two parts, the two parts being axially displaced, allowing flapper pin 22 and flapper 24 to move into position for opening before it has opened. The axial force of compressed shifting spring 26, through bearing 28 (which reduces resistance to rotation of the shifting spring) then quickly moves lower flow tube 29 downhole to make a space for opening of flapper 24. Flapper 24, supported by pin 22, is opened by the force of spring 16 acting on upper flow tube 18. Lower flow tube 29 must move rapidly enough to allow flapper 24 to fully open without interference from lower flow tube 29. The force of spring 26 is selected to be great enough to meet this requirement. After flapper 24 is open it is then covered in the open position by upper flow tube 18 as shown in FIG. 3.

FIG. 3 shows flapper 24 in the open position. Note that flapper 24 has the same center of the radius of curvature in the radial plane when open as the upper flow tube 18 and lower spring housing 25. This allows open flapper 24 to be located between upper flow tube 18 and lower spring housing 25. Lower spring 26 has expanded in the axial direction, moving lower flow tube 29. Snap ring 17 has moved in the axial direction such that radial compression of the snap ring has caused it to move radially outward into snap ring receptor 17 a. This causes upper flow tube 18 to be permanently locked in position, covering flapper 24. Torque stop plug 31 may be located at the distal end of lower spring housing 25 to prevent radial movement between lower sub 32 and lower spring housing 25. Lower spring housing 25 is joined to lower sub 32, which may be adapted to be joined to a tubular (not shown).

FIG. 4 shows cross-section 4 identified in FIG. 1. Lock housing 12 is shown behind the cross-section. Lower spring housing 25 concentrically encloses closed flapper 24 and lower spring 26. Flapper pin 22 supports flapper 24, which is shown in the open position in FIG. 7.

FIG. 5 is an isometric view of flapper 24 in a closed position with parts not shown that block the view of the flapper. FIG. 6 is an isometric view of the flapper in a partially open position. This view also identifies sealing surfaces 240 and 241 on the flapper shown in FIG. 8. When the flapper is closed, these surfaces mate with surfaces on upper flow tube 18 and lower flow tube 29 to form a hydraulic seal. Normally the sealing surfaces are covered with an elastomer or other type of sealing material. FIG. 7 is an isometric view of flapper 24 in the open position with parts not shown that block the view of the flapper.

FIG. 8 is a perspective view of the flapper 24. Sealing surface 240 engages an end of upper flow tube 18 and sealing surface 241 engages an end of lower flow tube 29 as shown in FIG. 9.

MODE OF OPERATION

The mode of operation is as follows. With the flapper closed, the formation is isolated and the flapper is sandwiched between the upper and lower flow tubes, effecting a bi-directional seal above and below the flapper.

When hydrostatic pressure is applied from above, the flapper shears a shear ring or pin or any other destructible retention mechanism via the lower flow tube which then moves axially downward. When the destructible element 30 releases, the lower flow tube 29 moves axially downwardly by virtue of biased spring 26, thereby allowing the flapper to freely rotate to the open position.

The upper flow tube 18, biased by a second spring 16 which is weaker than spring 26, pushes the flapper to the fully open position shown in FIG. 3.

Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims. 

I claim:
 1. An isolation valve sub for placement in a string of tubulars, comprising: a lock housing adapted for joining to a first tubular; an upper spring housing joined to the lock housing and a first spring enclosed in the upper spring housing; a lower spring housing joined to the upper spring housing and a second spring enclosed in the second spring housing and a spring stop for the enclosed spring; an upper flow tube concentric within the upper spring housing and adapted to move axially in response to force from the first spring; a lower flow tube concentric within the lower spring housing and adapted to move axially in response to force from the second spring; a destructible element adapted to receive axial force from the lower flow tube; a pivotably mounted flapper, disposed to apply force to the lower flow tube; and a lower lock housing joined to the second spring housing and adapted to be joined to a second tubular.
 2. The isolation valve of claim 1 further comprising a housing adapter disposed between the upper spring housing and the lower spring housing.
 3. The isolation valve of claim 1 further comprising a bearing disposed between the first spring and the upper spring housing.
 4. The isolation valve sub of claim 1 further comprising a snap ring disposed on the upper flow tube and being adapted to slidably move axially within the upper spring housing and expand radially to lock at a position in the upper spring housing;
 5. The isolation valve of claim 1 wherein the destructible element is positioned on the lower flow tube and restrains downward movement of the lower flow tube until a given force acting on the element is exceeded.
 6. The isolation valve of claim 1 wherein the lock housing, upper spring housing, lower spring housing and lower lock housing all have an outside diameter no greater than the outside diameter of the string of tubulars.
 7. The isolation valve of claim 1 wherein the valve includes a central flow path of a substantially constant diameter with no flow restrictions.
 8. A method for placing a tubular string in a well comprising: locating a plurality of isolation valves along the tubular string thereby forming isolated chambers within the tubular string filed with a gas; and placing the tubular string within a well with the isolation valves in a closed position.
 9. A method as claimed in claim 8 wherein the gas is air or nitrogen. 